Semiconductor for sensing infrared radiation and method thereof

Abstract

The bolometric sensing circuit includes a pixel array comprising pixels, each pixel comprising a sensor configuration to comprise a light receiving portion to convert incident photons into heat and a sensing portion integrated with the light receiving portion and having a resistance varying according to the converted heat; an output portion to output a common mode voltage that represents a voltage of the sensing portion from which accumulated heat has been removed in response to a heat removing voltage to thermally reset the sensing portion, and output a sensed voltage that represents a voltage of the sensing portion which has accumulated heat for an integration period after being thermally reset; and a processor to subtract the common mode voltage from the sensed voltage to produce a signal voltage that represents a change in resistance of the sensing portion due to the heat accumulated for the integration period.

What is claimed is: 
     
       1. A bolometric sensing circuit comprising:
 a pixel array comprising of a plurality of pixels, each pixel comprising of a sensor configured of a light receiving portion to convert incident photons into heat and a sensing portion integrated with the light receiving portion and having a resistance varying according to the converted heat, a mechanical structure that moves in response to an applied voltage that pulls the sensing area into intimate contact with a thermal sink such that the temperature of the sensor is equalized with the substrate, thereby thermally resetting the sensor; 
 an output portion configured to output a common mode voltage that represents a voltage derived from the sensing portion from which accumulated heat has been removed in response to a heat removing voltage actuated mechanical thermal reset of the sensing portion, and an output of a sensed voltage that represents a voltage of the sensing portion which has accumulated heat for an integration period after being thermally reset; 
 a memory configured to store the common mode voltage and the sensed voltage; and 
 a processor configured to subtract the common mode voltage from the sensed voltage to produce a signal representation that represents a change in resistance of the sensing portion due to the heat accumulated for the integration period, 
 wherein a read out of the common mode voltage and the sensed voltage occurs during one scan period in which desired number of pixels are read out, the one scan period includes a first period before the common mode voltage is read out and a second period after the common mode voltage is read out, and 
 the output portion is further configured to comprise: 
 a storage configured to store the common mode voltage for the first period and to store the sensed voltage for the second period; and 
 a switching portion configured to output the common mode voltage to the memory after the first period and subsequently output the sensed voltage after the second period. 
 
     
     
       2. The bolometric sensing circuit of  claim 1 , wherein the output portion is further configured to comprise:
 a first storage configured to store the common mode voltage; 
 a second storage configured to store the sensed voltage; 
 a first switching portion configured to output the common mode voltage to the memory; and 
 a second switching portion configured to output the sensed voltage to the memory. 
 
     
     
       3. The bolometric sensing circuit of  claim 1 , wherein the output portion is further configured to comprise:
 a first storage configured to store the common mode voltage; 
 a second storage configured to store the sensed voltage; 
 a third storage configured to store a common mode voltage or a sensed voltage of a temporal adjacent frame of a current frame; 
 a first switching portion configured to output the common mode voltage to the memory; 
 a second switching portion configured to output the sensed voltage to the memory; and 
 a third switching portion configured to output the common mode or sensed voltage present in the third storage. 
 
     
     
       4. The bolometric sensing circuit of  claim 1 , wherein the sensing portion is a single-crystalline silicon thin film. 
     
     
       5. The bolometric sensing circuit of  claim 1 , wherein the processor supplies a control signal to the switching portion for control.